Estudo das comunidades de nematoides como bioindicadores de distúrbio em sistemas agrícolas

• Autor(a) principal: Coutinho, Raul Rodrigues
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4427
• topic: Nematoides; Bioindicadores; Geoestátistica; Nematodes; Bioindicators; Geostatistics; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA

The cerrado is considered the last agricultural frontier of the country. therefore needs to implement more sustainable systems in order to minimize environmental damage. To assess its sustainability, there are several types of indicators, such as: physical, chemical and biological and nematodes communities. The aim of this study Was to use nematodes as bioindicators of disturbance in establishment of the crop-livestock-forestry system integration. A long-term experiment has been conducting at Embrapa Agrossilvipastoril (Sinop-MT). The experimental design Was a randomized block With 10 treatments and 4 replications. Forest Area and Natural Vegetation Were considered as a treatment controls. The treatments Were: 1-Forest (F); 2-Farming (F); 3-Livestock (L); 4- integration Crop-Livestock (CL); 5- integration Livestock-Farming (LF); 6- integration Crop-Forest (CF); 7- integration Livestock-Forest (LF); 8- integration Crop-Livestock- Forestry (iCLF); 9- integration Crop-Livestock-Forestry (iCLF); 10- Crop-Livestock- Forestry (iCLF). Six subsamples Were taken for each composite sample, and two samples Were taken per plot. The nematodes Were extracted from soil and identiñed. The nematode communities Were characterized as a ñmction of the total and relative abundance , diversity index and evenness of Shannon-Weaver and Simpson, wealth (D), maturity index (MI), modiñed maturity index (mMI), maturity index 2-5 (IM2_5), plant parasitic index (PPI), pattern of organic matter decomposition and dominance of nematodes practicing herbivory or feeding of microorganisms. The data Were analyzed by ANOVA and means Were separated using Tukey's test at the P< 0.05 signiñcance level to identify the effects of these systems on the nematode community. The group of nematode plant parasite Was dominating in both sampling. Mycophagous and Bacteriophages Were reduced after the implementation of the systems. About the Predators group, they Were in greater number of genres in the second collection. The 5- LF, 9-iCLPF systems and Forest Area had the smallest reducing of Omnivores nematodes population. The highest Values of diversity index and the Shannon-Weaver evenness Were found in 7-LF, 9-iCLF systems and Natural Vegetation. The 9- iCLF system increased all diversity indices. In addition to that, the 9-iLPF system enhanced evenness and richness parameters as Well. Unlike the 2-F and 4-CL systems had decreased the same parameters analyzed. The lowest Value of MI Was found in 2-F system and the highest were found in the systems 5-lf, 9-iclf system and Natural Vegetation. The IM, IMm, IM2_5 and IPP indices indicated Areas of Forest and Natural Vegetation as a environments stable reference areas. The measures of diversity and other indices studied showed the 9-iCLF system as a slightest disturbance in the environment. And the biggest Values in the 2-F system. Another Work about Geostatistic Was made at this paper. Geostatistical analysis is a methodology for the analysis of spatially correlated data. The semivariogram is the basic tool that supports the kriging techniques. Before that, the objective of this paper Was to demonstrate the geostatistics as a tool to improve the number and optimal sampling distance in order to have a representative analysis of nematodes in specifics areas. The sample Collecting Was made at the Experiment Area from Embrapa Agrossilvipastoril Sinop/MT. Nematodes Which ñtted in a semivariograma showed accurate information about distribution and spatial dependence. Through semivariogram analysis Was possible to ñnd an ideal sampling number for 5 nematodes genres (Aphelenchoides, Ditylenchus, Tylenchus, Acrobeles and Tobrilus) amongst the total genres found (25 genres). The semivariogram adjusted to nematode Aphelenchoides had the spherical model fitted to the data indicating a range of 43,11 meters. For DitylenchuS, Tylenchus, Acrobeles and Tobrilus the exponential model showed better fit, What indicated a spatial dependence of 50.97; 51.44; 44.79 and 39.67 meters, respectively. In order to get a good sampling, each sample must be collected using these range Values between samples previously showed. These Values indicated that, two composite samples per hectare using the range Values are necessary to have a representative sampling of Aphelenchoides, Acrobeles and Tobrilus genres. About Ditylenchus and Tylenchus genres, 3 sampling Would be needed per 4.942 acres. For the other genres, this paper Was not able of ñnding any spatial dependence. According to this Work, the geostatistics is an important tool for estimating the distance and optimal number of samples to evaluate nematodes populations in this area.